Control system



2 Sheets-Sheet l Mlm.

June 24, 1941. l. E. CQLE 2,246,505

CONTROL SYSTEM Filed Nov. l0, 1959 2 Sheets-Sheet 2 FIG. 2

jw-mw MARK/NG /M/ENTOR E. COLE Afro/Wgr Patented June 24, 1941 UNlTEDSTATES PATENT GFFICE CONTROL SYSTEM Application November 10, 1939,Serial No. 303,767

(Cl. 17S2) 2 Claims.

This invention relates to control systems and particularly to electricalcircuits involving a plurality of circuits to be controlled by certaincommon conditions.

The object of the invention is to provide economical means for certainswitching operations where speed and accuracy is essential. In aspeciiic embodiment of the invention herein used by way of example thepresent circuit is one in which great economy has been achieved by novelmeans. In this circuit, which is part of the control oi an interpolatedtelephone and telegraph system wherein the communication channel isnormally conditioned for telegraphic transmis-V sion, speech currentsmay take command and thereupon the condition of the channel must bechanged to one suitable for telephonie transmission. The switchingentailed must be accurate and rapid. Heretofore very expensive polartype relays have been employed and a plurality of switching segments ona rotary distributor have been used.

I have discovered that by using the novel means herein disclosed I canreduce the number of relays and distributor segments and thereby achievegreater accuracy at far less expense `and at the same time cut down onthe cost of maintenance.

A feature of the invention is a plurality of relays, one for eachtelegraphic channel, each hav-V ing a winding for driving it to markingand another winding for driving it to spacing. Each relay is providedwith a switching point which may be a distributor segment for connectingbattery to both its windings. There is a common grounding contactconnected to all the marking windings of the relays and a commongrounding contact connected to all the spacing windings of the relays.

Another feature is the use of a rectifier in the circuit of each of therelay windings which acts to prevent false operation of the relaysthrough the multiple connections to the said common grounding contacts.

The drawings consist of two sheets which, when placed as indicated inFig. 4, will constitute a diagram of a circuit in which the presentinvention is embodied.

Fig. 1 is in schematic form and Fig. 2 is in more detailed diagrammaticform. Fig. 3, shown on the same sheet with Fig. 2,-is a skeletonizedschematic circuit diagram showing only the essential elements of theinvention.

Referring irst to Fig. 3, it will be noted that three relays, I, 2 and3, are shown. There are two common contact making devices, 4 and 5. Thecontact making device 4 is marked marking and the contact making device5 is marked spacing. Thus, when the contact making device 4 is closedany one of the relays I, 2 and 3 may be driven to its marking, orleft-hand, contact and in the .same manner, when the contact makingdevice 5 is closed, such relays may be driven to their right-hand, orspacing, contacts. The manner in which these relays are moved is throughan individual contact making device 6 corresponding to relay I, lcorresponding to relay 2, and 8 corresponding to relay 3. Thus, if

the device 4 is closed, and the device ti is also closed, current willflow through battery, through the device E, the rectiiier the upperWinding of relay I to the marking contact 4. The relay 2 cannot operatethrough a path involving the rectiner I0, the lower winding of relay I,the lower winding of relay 2, the rectifier i2, the rectifier II and theupper winding oi relay 2 to marking contact 4 because the rectifier I2prevents currentin such a circuit. Likewise, relay 3 will not beoperated through a path including the lower winding of relay I and bothwindings of relay 3 because the rectier I4 prevents i'low of current insuch a circuit. If contact making device 5 is operated instead ofcontact making device 4, then when any one of the contact devices 6, l'or 8 is operated, the corresponding relay I, 2 or E will be driven toits spacing contact and, due to the use of the rectiiiers 9 to I4,inclusive, only that relay will operate whose individual contact makingdevice 6, 'l or is operated. Since the relays, such as I, 2 and 3, arerather expensive devices and the rectiers 9 to i4, inclusive, areinexpensive devices, this circuit will be considerably more economicalthan some other circuit which would achieve the same result through theuse of addi tional relays instead of the rectier devices.

As an example of how a circuit of this kind is used, the communicationsystem shown in Figs. 1 and 2 will be described.

A speech path I5 leads to hybrid coil I6 from which a path i1 foroutgoing speech leads to a Vogad I8. The outgoing speech then passesthrough a transmitting suppressor I9 and by means of an amplifierdetector 2t operates a chain of relays 2l, here labeled as a Voiceoperated switching circuit. This voice operated switching circuitcontrols a transmitting singing suppressor 23 so that the outgoingspeech can pass from the transmitting suppressor I9 through the delayand amplifier 22 and the transmitting singing suppressor 23 to thehybrid coil 24. From the hybrid coil 24 the speech reaches anotherhybrid coil 25 and thence goes through the radio transmitter 26 to thetransmitting antenna 21. Through radio transmission, the speech will bereceived at some distant point and, for purposes of explanation, it willbe assumed that the distant point has a receiving circuit similar in al1respects to the lower part of Fig. l and to Fig. 2. The speech,therefore, enters antenna 28, passes through a radio receiver 29 and arepeater 38 to a hybrid coil 3|. From the hybrid coil 3| the speech goesinto hybrid coil 32, thence through the receiving signal suppressor 33,the receiving repeater 34, low-pass lter and a path 36 to a hybrid coil,such as I6, whence it goes to the receiving subscriber over a line suchas I5.

That part of the circuit between and including the radio transmitter andthe radio receiver I5 is spoken of as a mutable link since it comprisesa signaling channel capable of, or liable to, change from internal orexternal cause which may give rise to interfering energy, or, morespecifically, subject to noise, fading or change of impedance.

The voice operated switching circuit 2| controls a control tone enabler31 so that tone from a source 38 is passed through the control toneilter 40 to the hybrid coil 25 and thus enables speech. Such control isindicated by the righthand line drawn from the top of the rectangle 2|and entering the control circuit 4I, where it is indicated by a dottedline within such rectangle, thereafter leaving this point and exercisingcontrol over the control tone enabler 21. The voice operated switchingcircuit 2| also controls the control circuit 4I, the transmitting signalsuppressor 23 and a switching point leading from the receiving switchingcircuit 42 to the transmitting suppressor I9. Thus, when speech comes inover the path I 5 and the voice operated switching circuit 2| isoperated, the control, which the receiving switching circuit 42 mighthave over the transmitting suppressor I9, is cut olf, the transmittingsinging suppressor 23 is enabled, and the control tone enabler 31 isoperated if the control circuit 4I has not interfered with this lastcontrol. It will be noted hereinafter that such interference is providedfor under certain specified conditions.

At the receiving end the control tone coming in as modulation of acarrier wave over antenna 28 passes through hybrid coil 3| and thencethrough telegraph band elimination lter and into a control tone amplierand filter 43, whence through the agency of receiving detector 44 itoperates the receiving switching circuit 42. The receiving switchingcircuit controls a normally open circuit between the telegraph bandelimination lter 45 and the receiving detector 44, including a speechamplier 45. This is provided so that when the control tone is rstreceived, the receiving switching circuit 26 will be operated therebyand then held operated thereafter by speech currents flowing through theamplifier 46. This means that the circuits 43 and 46 are both effectiveand operated in conjunction with each other to hold the switchingcircuit chain of relays operated.

In this connection, it will be noted that when speech rst comes on atthe distant transmitting end, the control tone enabler 31 is operatedand this allows tone of full volume to flow from the source of controltone 38 into the hybrid coil 25. After a delay, as provided by the delayand amplifier 22, the control tone compressor 39 operates to reduce thevolume of control tone being transmitted to the distant end. Thus, atthe receiving end the first eifect will be the reception of a very shortinterval of control tone at high amplitude followed by a reduction inthis amplitude when speech comes on.

The receiving switching circuit 42 also controls the receivingsuppressor 33 to open up the speech path, that is, to put the speechpath in condition to freely transmit speech currents. The receivingswitching circuit 42 also controls a normally closed path between theband-pass filter 41 and the telegrad 48 so that while speech is beingreceived the telegrad 48 will be disabled. At the same time, a receivingswitching circuit 42 controls the switching relay 50.

During pauses in speech, either when the subscriber at the distant endis talking into channel i5 or during the time when the subscriber onchannel I5 pauses during his talk out over antenna 21, the telegraphapparatus shown in the upper part of Fig. l is in operation. Thiscomprises perforators 5I and 52 working respectively into tapetransmitters 53 and 54 and thence into rotary distributor 55. Rotarydistributor 55 works into the control circuit 4I, which in turn,exercises control over the telegraph signal converter 53. A source oftelegraph signal tone is supplied to the telegraph signal converter 56by the source 51. Under control of the control circuit, this telegraphsignal tone is broken up into spurts corresponding to signals which arethen sent into the hybrid coil 24 and thence out over the radiotransmitter 21 where they will eventually operate the telegrad 48. Atthe distant end these telegraph signals in the form of spurts ofalternating current are received over antenna 28 and radio receiver 29and passed through the hybrid coils 3| and 32 to the band-pass lter 41.Thereafter the signals enter the telegrad 48 and are converted fromvarying strength alternating current signals to uniform strength directcurrent signals of practically the same length at which they werereceived over the antenna 2B. Each marking signal will result in theoperation of relay 49.

The operation of the telegrad is fully explained in the patent of Barneyet al., No. 2,238,028, granted April 15, 1941.

For purposes of avoiding mutilation of telegraph signals, sixth pulsecircuits 58 and 59 are provided to exercise a delay in the control whichthe voice operated switching circuit 2| has over the control toneenabler 31 under the condition when a telegraph code is completed withina given percentage of its total length. For a more complete descriptionof this function reference is made to Patent No. 2,207,720, issued July16, 1940 to Cole et al.

The direct current signals produced by the telegrad 48 operate thereceiving telegraph master relay 49, it being now assumed that the voicedoes not have control of the circuit and that receiving switchingcircuit 42 is not operated. Relay 5i] will be operated and, hence,relays 60 and 6| will be in the positions shown. Therefore, upon eachoperation of the receiving telegraph master relay 49, a circuit will beestablished from the armature and back contact of relay 6|) through thearmature and front contact of relay 49 and thence through the upperwindings of the three relays 52, 63 and 64. All three relays will bedriven to their marking contacts as shown. When a space signal is beingreceived by the telegrad 48, the relay 49 will be on its back contactand thus the lower windings of the three relays 62, 63 and 64 will beenergized and thus the relays will be driven to their spacing contacts.It will be noted that when the voice currents take charge of thecircuit, relay 50 will be released after an interval controlled by thetwo resistances 65 and 66 and the condenser 61 and thereupon the relays60 and 6| will be operated. Relay 6|] holds the three relays 62, 63 and64 operated continuously on their spacing contacts. Relay 6| places aground on conductor 68 to insure that relays 10 and 1| will remain ontheir spacing contacts so that the stepping magnets 12 and 13,respectively, cannot be energized during the time that speech hascontrol of the circuit.

When the telegraph circuit is operating, however, the receivingtelegraph line relay 62 will follow the incoming impulses and, throughthe continuous segment 14 and various short segments traversed by thebrush 15, will distribute these impulses to the proper selector magnets16 to 85, inclusive. The brush is moved by a shaft 86 controlled by themotor and synchronous equipment 81. The shaft 86 also carries a brush 88which connects battery to the two rectiers 89and 90 While the brush 15is distributing impulses to the magnets 16 to 80, inclusive, andlikewise the brush 88 connects battery to the rectiers 9| and 92 whilethe brush 15 is distributing impulses to the magnets 8| to 85,inclusive. Thus, if there are any marking impulses in the codes receivedwhile brush 15 is wiping over segments connected to magnets 16 to 8|),the relay 63 will close a circuit from ground through its armature andfront contact to conductor 93 and thus causes the operation of relay 1|to its marking contact. In like manner, relay 1I] is driven to itsmarking contact and these relays are of the polar variety which maintaintheir armatures as last placed until they aredriven to the otherposition. Thus, when the brush 15 has completed its task of distributingimpulses to the A printer, the brush 94 will make contact with segment95 and complete a circuit from ground through the armature and contactof relay 1| to the Winding of magnet 13 to cause the printing of thecharacter stored by the magnets 16 to 80. In like manner, after thebrush 15 has completed its task of distributing impulses to the Bprinter, the brush 94 will come in contact with segment 96 and cause theoperation of magnet 12 to print the character stored by the magnets 8|to 85.

As soon as the voice currents take charge of the circuit, the relay 50,after its period of hangover, will release and through the operation ofrelay 6| will place ground on conductor 68 to drive both relays 10 and1| to their spacing contacts.

The relay 64 is a corrector relay and, during the periods when it is onits spacing contact, causes the charging of condenser 91. When relay 64goes to its marking contact, it discharges this condenser through thesegments connected to either conductor 98 or 99 or, if the shaft 88 isin exact synchronism with the shaft of the distant rotary distributor55, then the discharge of the condenser 91 will be practically dividedequally between the two conductors 98 and 99. Under this condition therelay |00 will not operate. If, however, either conductor 99 or 98receives the full discharge of condenser 91 or a preponderance of suchdischarge, the relay |00 will operate to its right or left-hand contactand result in iinal operation of device |0| which here indicates eitherfast or slow operation of the L shaft 88 and represents means forbringing such shaft back into synchronism with the distant rotarydistributor 55.

What is claimed is:

1. A circuit arrangement including a plurality of relays each having afirst winding for driving the armature of said relay to a first contactand a second winding for driving the armature of said relay to a secondcontact, an energizing contact individual to each relay connected toboth windings of said relay, a common contact connected to the rstwindings of all said relays, a common contact connected to the secondwindings of all said relays and a rectifier in circuit with each windingof said relays, said relays being operated when their individualenergizing contacts and one of said common contacts are closed.

2. A control circuit including a plurality of relays each having awinding for driving said relay to marking, and a winding for drivingsaid relay to spacing, an individual contact for each relay for placingbattery on both said windings, a common ground contact for the markingwindings of all said relays, a common ground contact for the spacingwinding of all said relays and a rectifier in circuit with each windingof said relays to prevent false operation of said relays through themultiple connections to said common contacts.

IRA E. COLE.

